Tubular prostheses are used in body lumens to perform various functions. For example, a tubular stent may be used to maintain the opening of an esophagus that has been restricted by a tumor or a blood vessel restricted by plaque. Tubular grafts are used to substitute for or reinforce a weakened lumen, such as the aorta or other blood vessel that has been weakened by an aneurysm. In this latter technique, a graft of a knitted dacron may be used to advantage since the textured nature of the textile can induce blood clotting along the graft to contribute to the patency of the lumen formed by the graft.
Tubular prostheses for purposes such as the above may be positioned in the body lumen during a surgical procedure or may be delivered into the body by a catheter that supports the prosthesis in a compact form during percutaneous insertion and transport through body passageways to a desired site. Upon reaching the site, the prosthesis is expanded so that it engages the walls of the lumen. After this operation, the catheter is removed, leaving the device in the body.
The expansion technique may involve forcing the prosthesis to expand radially outwardly, for example, by inflation of a balloon carried by the catheter. Knitted, balloon expandable stents are discussed for example in Strecker U.S. Pat. No. 4,922,905, the entire content of which we hereby incorporate by reference. In another technique, the prosthesis is formed of an elastic material that can be arranged and held in a compact form for insertion and allowed to expand when in position by its own internal elastic restoring force. Knitted self-expanding stents are described in Strecker PCT EP 91/02194 and in Anderson U.S. Ser. No. 07/773,847, filed Oct. 9, 1991, the entire contents of both applications being incorporated herein by reference.